Issues with traditional construction methods include high cost, long duration, potential coordination errors and the financial risk in producing buildings for multi-family, student housing, hotels, etc. Also, improvements can be made in terms of safety, sustainability and quality of design with respect to multi-unit buildings. A new system of design based on mass produced components will be easier to scale and replicated to meet global housing demands.
There are currently three major approaches in attempting to improve over the problems mentioned above, namely, by using prefabrication, modular units or new, complex alternate systems of construction.
With prefabrication, prefabricated walls and building components are integrated into traditional building techniques. One of the downsides of such prefabrication is compatibility issues with on-site elements. Coordination of mechanical, plumbing, electrical and structural systems are often difficult because prefabricated parts were designed to specifications and any on-site alteration can lead to compromise of the performance or structural integrity of the prefabricated parts.
Additionally, specialized knowledge and/or equipment is typically needed for installation which may increase time and cost in the long run. Another downside is the schedule, inspection and delivery of these parts which requires close coordination with traditionally built elements.
Modular units are assembled in factories and trucked to the site. Modular units are lifted by cranes and attached together by varies means including welding, metal straps and bolts. Modular unit approach is generally project and program specific. This approach is inflexible for altering to fit new needs or other projects when the program deviates even slightly. High volume of the same exact modules and specifications will be needed for assembly line and supply chain to be cost effective.
Modular factories generally utilize the same labor force and use the same materials as traditional construction. That is, each modular unit is a piece of the overall building, but is constructed using the same building techniques as if the building was built at once rather than in smaller units. This results in savings mostly in time and does not provide lower labor and material cost. Quality is comparable to on-site construction since the process uses the same labor force and materials. This approach generally does not produce modules that are precise enough for multi-unit, multi-storied buildings and precision cannot be sustained for large volumes. Each slight deviation on the module may cause compounding issues on the construction site.
Whole unit modular approach is also limited by transportable distances. The possibility of damage and warping of module increases with distance traveled. The result is that modules may deform and exceed the tolerance allowed upon arrival on site where there are few options available for site adjustments. The inconsistency of modules at the site contributes to moisture, thermal and acoustic intrusion issues when assembled to create a whole building.
Generally, the new alternate systems have proven to lack flexibility and too complex and too expensive to scale to significant volume, and therefore success has been limited.